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NVD / CVE Program· CNA Linux

CVE-2026-31772: Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.14% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 6.12, 6.12.81, aba0aea354015794e8312dd7efe726967e58aefe.

Low priority for now. Upgrade to Linux Linux 6.12, 6.12.81, aba0aea354015794e8312dd7efe726967e58aefe or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync hci_le_big_create_sync() uses DEFINE_FLEX to allocate a struct hci_cp_le_big_create_sync on the stack with room for 0x11 (17) BIS entries. However, conn->num_bis can hold up to HCI_MAX_ISO_BIS (31) entries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller hci_conn_big_create_sync(). When conn->num_bis is between 18 and 31, the memcpy that copies conn->bis into cp->bis writes up to 14 bytes past the stack buffer, corrupting adjacent stack memory. This is trivially reproducible: binding an ISO socket with bc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will eventually trigger hci_le_big_create_sync() from the HCI command sync worker, causing a KASAN-detectable stack-out-of-bounds write: BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0 Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71 Fix this by changing the DEFINE_FLEX count from the incorrect 0x11 to HCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that conn->bis can actually carry.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
May 1, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 3th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel6.11.11 and later · before 6.12
  • linux linux kernel6.12.2 and later · before 6.12.81
  • linux linux kernel6.13.1 and later · before 6.18.22
  • linux linux kernel6.19 and later · before 6.19.12
  • linux linux kernel6.13
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd, 6.13affected
    • 91d19383b7ed035e22165ae5c836e50bb9f95fbe and later · before f5d446624345d309e7a4a1b27ea9f028d6a8c5d9affected · git
    • 42ecf1947135110ea08abeaca39741636f9a2285 and later · before aba0aea354015794e8312dd7efe726967e58aefeaffected · git
    • 42ecf1947135110ea08abeaca39741636f9a2285 and later · before eaf32002ca7b1ba51c9f140991fd9febe6de79f0affected · git
    • 42ecf1947135110ea08abeaca39741636f9a2285 and later · before bc39a094730ce062fa034a529c93147c096cb488affected · git
    • 6.12.2 and later · before 6.12.81affected · semver
    • 6.11.11 and later · before 6.12affected · semver
    • before 6.13not affected · semver
    • 6.12.81 and later · up to and including 6.12.*not affected · semver
    • 6.18.22 and later · up to and including 6.18.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.26.1.el10_26.12.0-211.26.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-31768May 1, 2026 · iio: adc: ti-adc161s626: use DMA-safe memory for spi_read()
    31Monitor
  • ← EarlierCVE-2026-31771May 1, 2026 · Bluetooth: hci_event: move wake reason storage into validated event handlers
    32Monitor
  • Later →CVE-2026-31773May 1, 2026 · Bluetooth: SMP: derive legacy responder STK authentication from MITM state
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux6.12Vendor (CNA)
Linux Linux6.12.81Vendor (CNA)
Linux Linuxaba0aea354015794e8312dd7efe726967e58aefeVendor (CNA)
Linux Linuxbc39a094730ce062fa034a529c93147c096cb488Vendor (CNA)
Linux Linuxeaf32002ca7b1ba51c9f140991fd9febe6de79f0Vendor (CNA)
Linux Linuxf5d446624345d309e7a4a1b27ea9f028d6a8c5d9Vendor (CNA)
almalinux:kernel6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.26.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.12.85-1 · Debian:13Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debuginfo0:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debuginfo-common-aarch640:6.12.0-211.26.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+2

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records